The invention relates to a cart for an energy supply unit, which can be arranged between an upper run and a lower run of the energy supply unit, as well as to an energy supply device comprising at least one energy supply chain and a cart arranged between an upper run and lower run of the energy supply chain.
Energy supply chains are used in different apparatus, machines and devices, especially where it is necessary to transport utilities, for example, power, water, air as well as power in the form of current with the aid of lines, tubes or similar from a fixed connection to a movable connection of a user. An energy supply chain can have one strand or several strands in which lines, tubings or other similar flexible lines are guided.
When the energy supply pathway is very long, the problem arises that due to the weight of the energy supply chain itself as well as the weight of the lines and tubes, the energy supply chain or the chain links are highly stressed. This is especially the case when an upper run of an energy supply chain lies on a lower run, so that, due to the movement between the upper run and lower run, high frictional forces arise which lead, on the one hand, to wear of the, and on the other hand to a resistance to movement, as a result of which the force or power necessary to move the energy supply chain is increased and there is a danger that breakage of the chain or of its connection points will occur. Especially in the case of very long pathways of an energy supply chain, the linking bonds of the links of the energy supply chain are subjected to high tensile and compressive forces.
In order to minimize the frictional forces between an upper run and a lower run can be achieved with the aid of a so-called guide shoe. Guide shoes are arranged at least on some of the links of the energy supply chain, to reduce the frictional resistance between the areas of the runs that rub against one another.
It is known from EP 0 725 228 A1 that a cart can be arranged between an upper run and lower run of the energy supply chain. The cart has wheels or similar which are suitable to roll at the same time on the top of the lower run and on the bottom of the upper run. For synchronous movement of the cart with the moving end of the energy supply chain, the cart has a pulley on each of its opposite ends. The movable connection, is connected to a pair of cables and then to the movable end of the energy supply chain. One cable is guided over one of the pulleys at one end and the other cable over the other pulley on the opposite end of the cart. The ends of the cables are joined to the local connection of the energy supply chain. With the movement of the moving connection, the cart is moved by one or the other cable.
The problem with such an arrangement is that, due to the stretching of the cable, synchronous movement cannot be achieved reliably. Moreover, there is a danger that the cable can jump out of the pulley, which can destroy the cable guide.
From WO 03/060346, an energy supply device is known which has at least one power guide chain composed of separate links. The power guide chain links are linked to one another by axes perpendicular to the longitudinal direction of the energy supply chain. A first end of the energy supply chain is fixed while the second end of the energy supply chain can be moved in this longitudinal direction.
A cart is arranged between the upper run and lower run of the energy supply chain.
This cart is connected functionally to the upper run in such a way that during the functional connection the cart is moved only by the upper run. As a result, increased operational safety is achieved since passive drive of the cart occurs. The expenditure for the structure as well as for the mounting of such an energy supply device is reduced. The cart has a return motion device to ensure that the cart is put into motion even when there is no friction or insufficient friction between the upper run and the cart to entrain the cart by the upper run.